.470 NE & 9.3 x 74R Pressure Testing Reloads.

Yesterday for the first time in my life I had a friend set up and perform pressure testing on my .470 NE DR and two 9.3 x 74R rifles, an O/U and a Ruger No 1. The results were very surprising, I present them for comments please, I am not suggesting that what we have here is correct or the absolute answer, but it has made me stop and rethink!

For the record I am not looking for increased velocity, I want around factory or just below, I need them to regulate but I do require them to be operating under “proof pressuresâ€.

All pressures were read using a Strain gauge over the chamber.

9.3 x 74R
First we established a bench mark using factory Norma 286 gr Alaska and Oryx and RWS 293 gr TUG all recorded pressures were in the 45,000 to 62,000 psi and velocities were 2300+ for the 286 gr and 2100+ for the 293 gr. The Norma Oryx had the highest pressure.

Reloads: 9.3 x 74R. All cases were RWS, full length sized, Remington 210 Magnum primers and Woodleigh 286 RN SP bullets.

My “Africa†load 62 gr IMR 4831 gave 2156 fps and 48,442 psi

IMR 4064 57 gr gave 2355 fps and 67068 psi
H 4831 66 gr gave 2167 fps and 57821 psi
H 4831 70 gr gave 2279 fps and 58146 psi

The last load was:
IMR 4831 66 grs gave 2253 fps and 54415 psi. This I must check for accuracy.

.470 NE
The benchmark was established with Federal factory 500 gr SP, we will confirm with Norma factory when it arrives.

Federal 500gr SP gave 1840 fps and 36000 psi

If tons per sq inch are converted to psi by dividing by 2204 (the number of lbs in an imperial Ton) this gives 16.33 Ton. Proof was 14 Ton!!!

Reloads: Once fired RWS brass 210 primers and Woodleigh 500 RN SP bullets.
Due to a computer error we failed to save a lot of velocities.

My “Africa†load IMR 4831 105 grs (previously recorded 1950 fps) gave 43752 psi with a second pressure spike of 39000 before the bullet had exited the bore!! This pressure trace scares the hell out of me. This is the load from Graeme Wright’s book that was recommended. Next we improvised with a cotton ball as a wad, pressure peaked higher at 49419 psi but the trace was “normalâ€.

H4831 117 grs gave 2138 fps and 62957 psi
H4831 114 gr gave ……...fps and 53810 psi
H4831 103 grs gave …… fps and 59577 psi with cotton wad

IMR 4350 105 grs gave 2200 fps and 63183 psi with cotton wad (Heavy recoil!)
IMR 4350 95 grs gave 1900 fps and 36825 psi with cotton wad. This showed promise.
We then repeated this load three times, we got similar fps but all pressures were 48500 –49734 psi.

Next I get RL15 and foam wads.

I would be very interested in hearing any ones comments.

John

What sort of strain gauge or pressure transducer and pressure barrel setup are you using?

Amazing numbers there. I do not know what to say about this.

John:

Thanks for the post. It's interesting data.

quote:

Originally posted by John Hipwell:
If tons per sq inch are converted to psi by dividing by 2204 (the number of lbs in an imperial Ton) this gives 16.33 Ton.

That simply doesn't work because it attempts to equate two completely difference measuring systems (strain gauge vs Base Copper Crusher) that are used to measure two completely different things (chamber pressure vs bolt thrust). The measured results are not convertible to each other.

You're measuring chamber pressure radially with a strain gauge. In standardizing their cartridges, the British never measured chamber pressure at all. Rifle cartridge pressures were standardized in Base crusher guns that measured bolt thrust (the copper pellet was crushed between the breech face and case head) - an axial measurement. Chamber pressure is measured radially - on the chamber sidewall.

When working with the British cartridges, always remember - the original pressure standards are NOT chamber pressure, nor can they be readily converted to chamber pressure.

quote:

Proof was 14 Ton!!!

No. The .470 was standardized at 14 tons maximum service pressure. Under the British Proof Law of the day, proof loads were required to produce 130% to 145% of service pressure - not less than 18.2 tons, nor more than 20.3 tons for a .470. This is the pressure that your Vaughan was proved to.

The central issue here is correlation. What you need to be using as reference are the current CIP standards for both cartridges.

Current CIP standards (ignore the SAAMI standards - the dimensions aren't even the same) for the .470 are 39,160 PSI MAP (maximum average pressure) and a proof pressure of 48,950 PSI.

Current CIP standards for the 9.3X74R are 49,312 PSI MAP, and a proof pressure of 61,641 PSI.

The above are in PSI (measured by piezo electric transducer) not CUP. A strain gauge isn't the same measuring system either. As to how strain gauge measurements correlate to piezo electric - I don't know enough to even try. I hope your friend is well up on that score.

This string certainly points up the futility of using conventional pressure signs as a guide in handloading for large bore double rifles. By the time conventional pressure signs begin to appear, you're over proof pressure by a wide margin.

Keep us posted on your progress.
---------------------------------------------
"Serious rifles have two barrels, everything else just burns gunpowder."

Ripp
Please go to the attached link for more info on the system we were using.
http://www.shootingsoftware.com/pressure.htm

John

400 NE
Thanks for your input. I stand corrected on Service Pressure V Proof Pressure, my mistake.

I understand that CUP is different I fell into the trap of trying to compair results.

I will not try and correlate results from different systems, but surely I should be able to conpair my results from load to load? Factory ammo gives us a bench mark that we can only assume is safe, now my reloads are way to high, in conparison, why?

Thanks for the CIP standards in psi. I assume that we can compair my results with them?

John

quote:

Originally posted by John Hipwell:
I will not try and correlate results from different systems, but surely I should be able to conpair my results from load to load?

That seems reasonable to me.

quote:

Factory ammo gives us a bench mark that we can only assume is safe, now my reloads are way to high, in conparison, why?

John, I sincerely wish I had an answer for you. Now we're getting into details where I don't have one. I've never messed with a strain gauge system. All I can say is, try the RL 15 and filler and see what happens. In .500/.465 (also a 75 Cordite cartridge very similar to .470) I recently worked up from 84 grains RL 15, Kynoch foams wads, Fed 215 primers and 480 grain Woodleighs. Velocity became excessive beyond 86 grains.

quote:

Thanks for the CIP standards in psi. I assume that we can compair my results with them?

Yes, you should be able to. Again though, I don't know how strain gauge/piezo electric transducer data correlates, but a common sense approach would be to use Euro factory ammo as a baseline. As I said, CIP standards are law in Europe. Established MAP is what sets proof pressure - it's 125% of MAP. CIP supposedly spot checks pressures of factory cartridges there. It is ILLEGAL to sell factory ammunition there that exceeds CIP standardized pressure. So theoretically, Euro factory ammo should be within spec...we hope.

Perhaps it's also worth noting that CIP and SAAMI protocols for transducer placement are not the same.
----------------------------------------------
"Serious rifles have two barrels, everything else just burns gunpowder."

John:

Just a thought...since you're in Canada, how hard would it be to ship ammunition to the UK?

Once you have what you think is a good load that shoots well in your rifle and have tested it in the strain gauge system, you could have it pressure tested in a CIP spec piezo electric transducer gun. The Birmingham Proof House offers this service. They say they'll pressure/velocity test 10 rounds for 49 GBP. Same pressure guns that ammo manufacturers over there have to submit samples of their factory ammo to be tested in. For sure they have one in .470, and I imagine also 9.3. I'm fairly sure that Kynoch offers this service as well.

I have no idea how difficult getting it there would be, but I thought it might be easier for Canadians than for us.
---------------------------------------------
"Serious rifles have two barrels, everything else just burns gunpowder."

John, interesting data. Your 9.3 loads seem fine except for the IMR 4064 load. Your 470NE loads are about 300fps above the factory loads so it is not surprising that the pressures are much higher. Interesting data about the type of filler used.I don't know what gun you have but this is one of the reasons I shoot modern guns even if they are in traditional calibers.
Peter.

quote:

Originally posted by Peter:
John, interesting data. Your 9.3 loads seem fine except for the IMR 4064 load.

No, neither handloads or factory tested within limits.

quote:

Your 470NE loads are about 300fps above the factory loads so it is not surprising that the pressures are much higher.

The Federal factory load tested within limit, but was 200 fps below standard velocity so it does not represent a usable benchmark. Only a factory load that produces standard velocity would be.

quote:

I don't know what gun you have but this is one of the reasons I shoot modern guns even if they are in traditional calibers.

This statement doesn't make any sense.
-----------------------------------------------
"Serious rifles have two barrels, everything else just burns gunpowder."

John,
Thanks for the link describing the system. Glued on strain gage then.

The article did say that attaching the gage to a non cylindrical area such as the flared double rifle chamber area is prone to erroneous estimation of pressure from the machine "algorithms" generating the pressure tracings. It requires special attention to calibration with a known pressure. A real pressure. You don't have one.

One problem is, as 400NE points out, the poor quality factory ammo by Federal chosen as a calibration standard, and how do you know the pressure estimation for it at 36,000 psi is anywhere near reality? That is merely an estimate based on a possibly flawed system. A velocity of 1840 fps proves the poor quality of the ammo. I got velocities of about 1850 to 2100 fps with Federal factory 470NE ammo depending on whether I settled the powder noseward or baseward in the case before firing it: RL-15 about 85 grains, F216 special hot primer, and a lot of air space.
No good.

My other problem with the data, just from the 470NE familiarity side of it, is the high charge of H4831, 117 grains, that gives only 2138 fps: more usual would be 108 to 110 grains of H4831 for velocity around 2100 to 2125 fps where most modern doubles with 24" barrels will be shooting properly.

Powder lots do vary. Match of bullet diameter to groove diameter does vary. Brass internal volumes, et cetera gun and ammo factors.

My confidence in this strain gage system has not been bolstered.

There is a great deal of confusion when trying to compare pressure readings with different equipment. Basically you can’t compare any of the different methods directly.
Hear is a good bit of info from Oehler.
http://www.oehler-research.com/model43.html
Bill

In the "For whatever it's worth category"...

My Chapuis UGEX 9.3 was re-regulated by JJ a few months ago. The load used was 70.0 gr. H4831, primers Rem 9 1/2 M under a Nosler 286 Partition, S&B brass. The load chronographed right at 2350 fps over my Oehler 35P system. The velocity tracked very closely to that predicted by Hodgdon, so I would expect the pressures to be very close as well. Hodgdon predicted the velocity at 2232 fps and pressure 36,800 CUP. As noted earlier, CUP and CIP won't compare, but I am of the opinion that at 36,800 CUP, the load is safe. More confidence factors; First, Hodgdon published it, which would be the first vote of confidence. Secondly, if the load is "over pressure", or at least of some concern, I would have exspected JJ to make some comment, but none was received. A third confidence factor is the fact that it is a full case of H4831, a slow powder to boot, which is why I chose that powder in the first place. No reason to expect high pressure, and no filler needed. Finally, the velocity is a direct indication of the pressure of the round, and that also was OK. BTW - You need to use a magnum primer for this powder in the 9.3 case. I haven't needed a magnum primer with this powder in either the .270, or .338 Win, but it absolutely is needed in the 9.3 case. Trust me on this one! I don't know what pressures your rifle will generate, but again, FWIW, the chambers in my 9.3 are minimum, or near minimum. Minimum chambers would also tend to create maximum pressures, and none have been noted to date. In this rifle, fired brass will chamber in either chamber, so neck sizing is all I am using. DuaneB

400NE I not sure what point you are making, other than throwing mud, but here is the statement:

quote:

9.3 x 74R
First we established a bench mark using factory Norma 286 gr Alaska and Oryx and RWS 293 gr TUG all recorded pressures were in the 45,000 to 62,000 psi

He then gives several loads that fall within that range, hence my statement that the loads seem fine (except for the IMR 4064 load which came in above the range that he quoted.
My statement about: this is one of the reasons I shoot modern guns even if they are in traditional calibers which you say makes no sense, makes perfect sense to me because significant excessive pressures (or pressure variations)using modern powders and bullets in a 100 year old gun would be of major concern to me. However, with a modern double I could very easily choose to use a load to the upper end of the pressure spectrum. For example, I do use GS Custom FN solids in my doubles while many folks say, probably quite rightly, that you should not do that in an older gun. Now, I don't know what is so hard about all that, but having explained my thinking I choose not to engage in any more discussions with you on this thread.
Peter.

John:

Regarding the 286 grain 9.3, it's interesting that both Nosler and Norma list only propellants faster burning than H4831. Nosler lists RL 15, VV N-150, and Varget. Norma lists only Norma 201, 202, 203B, and URP. There's probably a reason for that. Since you're going to try RL 15 in the .470, I'd try it in the 9.3 and see what happens. For the Partition, Norma lists a min charge of 54 grains, and a max charge of 58.
----------------------------------------------
"Serious rifles have two barrels, everything else just burns gunpowder."

rip...in a ruger # 1 what would you run the norma brass necked up to 400 NE @ topps? 60,000 psi? maybe get 400 @ 2200+

In my 9,3 Chapuis with a 270 Speer 59gr of RL 15 shoots very good.

I use 65gr of IMR 4831 with 285/286gr bullets, including the Partition and Woodleigh Softs and Solids.

John, has any Norma ammo hit Canada yet? Some is here now, inlc 470 in the PH load and the reg hunting line. From all that I learned from my chrono thread, I wouldn't use any Federal as factory benchmark but I would use Norma, either load. I hurried off an email to the rep of my gunmaker asking him to forget about Cape Shok and regulate on Norma.

This is one of those no-win topics!

Whether it is CUP or strain (movement) in the barrel with a strain gage, they are both indications of pressure, which is not just a radial or longitudunal physical property.

I would think that to get semi-accurate strain pressure correlations that a barrel would need to have a long, straight shank such as on a bolt-action rifle. Trying to do the measurements on a sloping profile double rifle barrel would seem quite a stretch of the concept used in strain measurements.

Trying to correlate your strain measurements with factory loads is a stretch in itself as you don't really know what the factory load pressures are to begin with as they probably used a test barrel only having a very distant relation to the barrels/rifling/chamber dimensions/etc. of your double rifle.

It is appreciated that you have tried this but the high pressure readings compared to the "factory standard" reading may not and probably doesn't have any basis in reality.

With the typical paper-thin 470 cases and a tight chamber, if you were actually operating at such high pressure, the cases would probably start to stick in the chamber.

As long as you are using some "typical" powder for your 470, the velocities are near the "nominal standard" I doubt you could ever get to those high pressures. My 470 500 gr. loads are just shy of 2200 fps and the fired cases pop out even in the much-dreaded and over-stated African heat!

I don't mean this as being disrespectful, but you may have over-analyzed a non-issue.

Good morning all.
Thanks for all the comments, some points of clarification.

Shipping ammo from Canada to UK Proof House will be as tougth and expensive as doing it from the US. A good idea, and I may do that at the finish.

Primers: I had a typo, I was using Rem 215 Magnum primers in all my loads.

Norma ammo: Still waiting for this to arrive in Canada, we have a large quanity on BO and intend to test it with this system as soon as it arrives.

I collected some RL15 last night and will load and test with this as soon as I get some foam wads. I can't do any more testing until my buddy returns from Elk hunting any way.

I still maintain that I should be able to conpair results between factory ammo and reloads when all the results come from the same gun under the same conditions. I am not trying to compair my results with reloads, against a manufactures published figuars. I agree that the Federal ammo is crappy to say the least but it is the only "standard" I have right now.

John

quote:

Originally posted by Will:
This is one of those no-win topics!

Whether it is CUP or strain (movement) in the barrel with a strain gage, they are both indications of pressure, which is not just a radial or longitudunal physical property.

I would think that to get semi-accurate strain pressure correlations that a barrel would need to have a long, straight shank such as on a bolt-action rifle. Trying to do the measurements on a sloping profile double rifle barrel would seem quite a stretch of the concept used in strain measurements.

Trying to correlate your strain measurements with factory loads is a stretch in itself as you don't really know what the factory load pressures are to begin with as they probably used a test barrel only having a very distant relation to the barrels/rifling/chamber dimensions/etc. of your double rifle.

It is appreciated that you have tried this but the high pressure readings compared to the "factory standard" reading may not and probably doesn't have any basis in reality.

With the typical paper-thin 470 cases and a tight chamber, if you were actually operating at such high pressure, the cases would probably start to stick in the chamber.

As long as you are using some "typical" powder for your 470, the velocities are near the "nominal standard" I doubt you could ever get to those high pressures. My 470 500 gr. loads are just shy of 2200 fps and the fired cases pop out even in the much-dreaded and over-stated African heat!

I don't mean this as being disrespectful, but you may have over-analyzed a non-issue.

Ok... I am the buddy that has been helping John with the strain guage. I am aware of the issues that occur with using a glued on strain guage on a non-standard barrel.

The whole purpose was to test a load presumed to be safe and below factory maximums (Federal factory). I know that it’s not the best ammo to benchmark but it’s all I had available at the time.

Being that I cannot guarantee that the readings are exact, I can still get a reading. The Federal factory showed a consistent reading for a number of rounds and gave us a "number".

All the reloads that John then used also gave us a reading and showed us that the reloads then gave us a higher than Federal pressures.

Getting away from listing the numbers a "PSI" or "CUP" it still gives us a comparison. In reality loaded ammo should be still near to Federal factory numbers.

quote:

Originally posted by boom stick:
rip...in a ruger # 1 what would you run the norma brass necked up to 400 NE @ topps? 60,000 psi? maybe get 400 @ 2200+

Since the 9.3x74R CIP pressure spec is 49,300 psi MAP (3400 bar x 14.5 psi/bar) I would presume to calculate loads giving 50,000 psi for the Ruger No.1 and 40,000 psi for a double rifle. Real pressure determinations will come whenever it goes Big Time.

I've got other rifles to push harder with.
The 400 Nitro Express (Original or Aboriginal Missing Link) means moderation all around.

John and m_s, I agree that your setup should allow you to make comparisons betwen different loads in your two rifles. The problems seem to arise when you extrapolate from that data and use the "numbers" to compare against published data, in reloading manuals for example. The real issue in doubles however, is finding loads that shoot well in your rifles. Most doubles do not allow the user to easily regulate his barrels, so the tuning is done by reloading. Your 9.3x74R might allow you to do this. My O/U does. So, the trick is to use the data that you have, both from reloading manuals and your own data, and develop loads that shoot to your satisfaction, within safety limits. Your data on the different types of filler was certainly interesting.
Peter.